CVE-2018-21147 in D7800
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D7800 before 1.0.1.34, R7500v2 before 1.0.3.26, R7800 before 1.0.2.42, R8900 before 1.0.3.10, R9000 before 1.0.3.10, WNDR4300v2 before 1.0.0.54, and WNDR4500v3 before 1.0.0.54.
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Analysis
by VulDB Data Team • 06/01/2024
This vulnerability represents a critical stack-based buffer overflow affecting multiple NETGEAR networking devices that operate under a specific software version threshold. The flaw exists within the web management interface of these routers and is exploitable by authenticated users who possess valid credentials for accessing the device's administrative functions. The vulnerability stems from inadequate input validation mechanisms that fail to properly check the length of user-supplied data before copying it into fixed-size stack buffers. This condition creates a scenario where malicious input can overwrite adjacent memory locations, potentially leading to arbitrary code execution or system crashes. The affected models include several popular NETGEAR router series including the D7800, R7500v2, R7800, R8900, R9000, WNDR4300v2, and WNDR4500v3, all of which require authentication to exploit the vulnerability. The specific versions mentioned indicate that these devices were released with insufficient security controls in their web interface implementations. This vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is classified as a common weakness in software development practices that fail to properly manage buffer boundaries. The attack surface is particularly concerning as it requires only authentication to the device's web interface, meaning that an attacker who has obtained valid login credentials could leverage this flaw to gain deeper control over the affected devices. From an operational perspective, this vulnerability poses significant risks to network infrastructure security, as compromised routers can serve as entry points for broader network attacks or be used to conduct man-in-the-middle operations. The impact extends beyond simple device compromise since routers serve as critical network gateways, making this vulnerability particularly dangerous in enterprise environments where these devices often control access to internal networks. The vulnerability aligns with ATT&CK technique T1068, which involves exploiting legitimate credentials to gain access to systems, and could potentially lead to techniques such as T1059 for command execution or T1071 for network communication. The affected devices typically support various network protocols and services, making the potential attack vectors more diverse. The authentication requirement, while seemingly limiting, is problematic because many users maintain default credentials or reuse passwords across multiple devices, making successful exploitation more likely in real-world scenarios. Organizations should note that the vulnerability affects not just individual devices but entire product lines, requiring comprehensive remediation efforts across all affected models. The patching process for these devices requires careful consideration as many of these routers are deployed in remote locations or within environments where physical access is limited, complicating the update process. Security professionals should prioritize identifying and updating all affected devices within their networks to prevent potential exploitation by threat actors who may have already gained access to valid administrative credentials through various means including credential theft, default credential usage, or social engineering attacks.
This vulnerability demonstrates a fundamental flaw in the software development lifecycle where buffer overflow protection mechanisms were not properly implemented or tested within the web interface components of these networking devices. The stack-based nature of the buffer overflow indicates that the vulnerable code likely involves functions such as strcpy, sprintf, or similar string manipulation routines that do not perform adequate bounds checking before copying user input into fixed-size buffers allocated on the stack. The fact that this vulnerability affects multiple models from the same manufacturer suggests a systemic issue in the development process where similar code patterns were reused across different device firmware versions without proper security review. From a security architecture standpoint, this vulnerability violates the principle of least privilege and input validation, as the web interface should have implemented proper sanitization and length checking for all user-supplied parameters. The affected devices operate in environments where they are expected to maintain high availability and security, making this vulnerability particularly concerning as it could lead to persistent access or complete device compromise. The vulnerability's classification under CWE-121 highlights the long-standing nature of this class of flaws in embedded systems and network devices, where memory management and buffer handling are often overlooked during development cycles. Organizations should consider this vulnerability as part of a broader pattern of security issues affecting network infrastructure devices, particularly those that have not received regular security updates or patches. The exploitation of this vulnerability could enable attackers to modify router configurations, redirect network traffic, or establish persistent backdoors within the network infrastructure, making it a critical concern for network security teams. The fact that the vulnerability affects firmware versions released years ago indicates that many organizations may still be running unpatched devices, creating a persistent attack surface that threat actors can exploit with relatively low effort.
The operational impact of this vulnerability extends beyond immediate device compromise to encompass broader network security implications that affect enterprise and home network environments alike. When exploited, this buffer overflow could allow authenticated attackers to execute arbitrary code on the affected devices, potentially leading to complete loss of network control or data exfiltration capabilities. The vulnerability's presence in devices that typically serve as network gateways means that successful exploitation could enable attackers to monitor network traffic, redirect connections, or even create false network services to deceive users. Organizations should be particularly concerned about the potential for this vulnerability to be exploited as part of larger attack campaigns where threat actors first gain initial access through credential compromise and then escalate privileges using this buffer overflow. The affected device models are commonly deployed in both enterprise and residential environments, making this vulnerability relevant across multiple threat scenarios and attack vectors. The exploitation of this vulnerability could also enable attackers to modify DNS settings, create unauthorized network access points, or disable security features that protect the network from external threats. From a compliance perspective, the presence of this vulnerability in network infrastructure devices could potentially violate security standards and regulatory requirements that mandate proper vulnerability management and patching procedures. The vulnerability's requirement for authentication means that organizations should implement strong credential management practices and consider implementing additional security controls such as multi-factor authentication or network segmentation to limit the potential impact of credential compromise. Security teams should also consider implementing network monitoring to detect unusual network behavior that might indicate exploitation attempts or successful compromises of these devices. The long-term implications of this vulnerability suggest that organizations should establish more robust processes for tracking and managing security vulnerabilities in network infrastructure devices, including regular inventory audits and automated patch management systems to prevent similar issues from affecting their environments.